EMF sensor with protective sheath

ABSTRACT

A rugged sensor and method for manufacturing such, for use in hostile environments, the sensor exhibiting high mechanical strength to protect the sensor from physical damage. The sensor system also including a modular component that may variously be connected to the sensor to extension thereof, the modular component also exhibiting high mechanical strength to protect electrical conductors located therein.

PRIORITY DOCUMENT

This application is a continuation in part of and claims the benefit ofthe filing date of U.S. patent application Ser. No. 10/736,766 filedDec. 16, 2003 now U.S. Pat. No. 7,131,768.

FIELD OF THE INVENTION

The present invention relates to a sensor with electrical conductorsattached thereto for transmitting a signal, and more specifically to theconstruction of a sheath formed of a material exhibiting high mechanicalstrength for protecting the device from physical damage.

BACKGROUND OF THE INVENTION

Thermocouples are temperature measuring devices which measuretemperature by employing dissimilar metal conductors joined at a pointor junction where the temperature is to be measured with free endsconnected to an instrument to measure a voltage generated across thejunction of the dissimilar metals. The bimetallic junction of dissimilarmetals has been formed of various metals which provide a thermoelectricdifferential between the two metals upon exposure to heat.

Conventional devices use a variety of materials to produce thermocouplesensors with high operating temperatures. The various metals used toform thermocouple sensors suffer from the detrimental effects ofcontamination, ionic migration, sublimation, oxidation and substantialdecrease in mechanical strength with increasing operating temperatures.Current sensors are thus limited to an operating envelope of less than1090° C. (1994° F.) to ensure long term, stable output with minimumdrift in resistance. Higher temperature sensors can operate totemperatures up to 2370° C. (4298° F.) but are either limited tospecific environmental conditions (such as for instance: a vacuumenvironment, an inert gas environment, or a hydrogen atmosphere) and/ormust be limited to short term operation to prevent premature failure.This temperature operating range has limited the application of thesesensors in hostile, high temperature systems such as those commonlyencountered in the aerospace, petroleum and glass industries.

Prior art thermocouple sensors have had the disadvantage of melting atfairly low temperature and have required insulation and varioussheathing systems to protect the thermocouple during operation atprolonged elevated temperatures. However, this sometimes results inundesirable reactions between the metals in the thermocouple sensor andthe materials used in the insulation and sheathing systems.

The problems of undesirable reactions in thermocouple sensors have beenaggravated by the temperatures encountered in nuclear reactor systems,rocketry heat sensors, high-temperature and vacuum processing and otherapplications where temperature measurements at or above 1500° C. (2730°F.) are involved. Thermocouples have utilized sheathing and insulationin an effort to prevent the disintegration of the thermocouple in suchsystems. The insulation and sheathing systems have the furtherdisadvantage of resulting in time delays in obtaining temperaturereadings due to the insulation and mechanical packaging designedimplemented to prevent failure resulting from such problems as gasleakage at the thermocouple sheath seals, cracked sheaths and othermechanical limitations imposed by ceramic insulated metal sheathedthermocouple sensors.

Prior art bimetallic bare sensor combinations, such as those formed fromtungsten and rhenium have generally not proven to be uniformly reliableor to have a useful operational life at extended temperatures due tobreakage of the thermocouple hot junction upon initial heating anddrifts in EMF temperature relationships. These problems are believed tobe the result of thermal and chemical phase transitions and ofpreferential evaporation of one of the metals in the bimetallic sensor.These sensors are thus limited to vacuum, inert, or hydrogenatmospheres.

Attempts to extend the operational range of thermocouples have typicallybeen limited to use of insulation and sheathing techniques or increasingthe high temperature properties of known materials through alloyingprocesses or coatings, the disadvantages of which have been discussedabove.

High melting, noble metal thermocouples made of e.g., platinum (Pt),rhodium (Rh), palladium (Pd), iridium (Ir) and alloys thereof are knownin the art. For example, some widely used thermocouples for measurementof temperatures above 1000° C. (1830° F.) are: (Pt/Pt—13% Rh);(Pt/Pt—10% Rh); and (Pt—6% Rh/Pt—30% Rh). Each leg of the thermocoupleis made of a wire or thin film of Pt and/or Pt—Rh. The EMF-temperatureresponses for these devices, the basis of temperature measurement viathermocouples, are moderate and oxidation resistance is good. Thesethermocouples can be used with moderate to severe drift (i.e., a changein EMF with time due to any cause such as composition change, oxidationor chemical attack) up to 1500° C. (2730° F.). Other noble metalelements, e.g., palladium and iridium, and precious metal elements, e.g.gold and silver or alloys thereof with platinum are also useful to formthermocouples. Such thermocouples, however, are not widely used becausethey are more susceptible to oxidation than platinum, and degrade bydrift caused by selective oxidation.

Some of the characteristics of platinum can be improved by the usualalloy hardening method of adding a metal to the platinum base, followedby heat treatment. However, problems can occur after alloying. Forexample, when a high concentration of any alloying element is added tothe platinum base, the electrical properties of the resulting platinumlimb become inferior; at the same time the hardening phase willpartially or totally dissolve into the base at high temperatures, thusthe effects of the hardening action will be reduced.

Dispersing oxides of transition metals or rare earth metals within nobleor precious metals is an example of a method of creating thermocouplematerials with the desired extended temperature properties. Forinstance, dispersion hardened platinum materials (Pt DPH, Pt—10% Rh DPH,Pt—5% Au DPH) are useful materials because they achieve very high stressrupture strengths and thus permit greatly increased applicationtemperatures than the comparable conventional alloys.

Dispersion hardening (DPH) creates a new class of metal materials havingresistance to thermal stress and corrosion resistance that is evengreater than that of pure platinum and the solid solution hardenedplatinum alloys. When operational life, high temperature resistance,corrosion resistance and form stability are important, a sensor can bemanufactured of DPH platinum and can be used at temperatures close tothe melting point of platinum.

Dispersion hardened materials contain finely distributed transitionelement oxide particles which suppress grain growth andrecrystallization even at the highest temperatures and also hinder boththe movement of dislocations and sliding at the grain boundaries. Theimproved high temperature strength and the associated fine grainstability offer considerable advantages.

DPH of platinum has been developed and applied to for instance, theglass industry. For instance, zirconia grain stabilized platinum hasbeen used in the glass industry for the construction of a sheet ofmaterial. This approach however, has not previously been used in themeasurement field. For instance, the glass industry is focused onstability of the material at high temperature, whereas in themeasurement field not only is material stability at high temperature aconcern but signal repeatability and quality are critical. In addition,some of the various DPH of platinum approaches taken have utilized apowder material that cannot be utilized and manufactured into a wire foruse in a measurement device. Therefore, these techniques are not usablefor the measurement field.

Platinum: Platinum-Rhodium Thermocouple Wire: Improved Thermal Stabilityon Yttrium Addition Platinum, By Baoyuan Wu and Ge Liu, Platinum MetalsRev., 1997, 41, (2), 81-85 is incorporated by reference. The Wu articlediscloses a process of dispersion hardening platinum for aplatinum/platinum-rhodium thermocouple wire which incorporates traces ofyttrium in the platinum limb.

As described in the Wu article, the addition of traces of yttrium toplatinum as a dispersion phase markedly increases the tensile strengthof the platinum at high temperature, prolongs the services life andimproves the thermal stability. Yttrium addition prevents the growth inthe grain size and helps retain the stable fine grain structure, as thedispersed particles of high melting point resist movements ofdislocations and make the materials harder. The strength of a materialis related to the movement and number of the dislocations.

In order to harden metals, the movement of the dislocations needs to berestricted either by the production of internal stress or by puttingparticles in the path of the dislocation. After the melting andannealing process, the majority of the trace yttrium (in the dispersionphase of the platinum) becomes yttrium oxide, which has a much highermelting point than platinum. When the temperature is near the meltingpoint, dispersion hardened particles fix the dislocation, thus hardeningthe platinum and increasing its strength.

At the same time the grain structure becomes stable after dispersionhardening and there is also microstructural hardening. The dispersedparticles affect the recrystallization dynamics, inhibit rearrangementof the dislocations on the grain boundaries and prevent the movement ofthe grain boundaries. Therefore, this dispersion hardened platinumpossesses a stable fine grain structure at high temperature.

The Wu thermocouple meets the output requirements of the Type S standardfor thermocouples—those made of Pt: Pt-10% Rh—whose manufacturingtolerances are prescribed by the International ElectrotechnicalCommission (I.E.C.). Because the platinum-rhodium leg of a conventionalthermocouple has much higher tensile strength than a pure platinum leg,the Wu thermocouple dispersion hardened only the platinum leg in orderto increase the tensile strength of the platinum leg to balance thestrength of the two legs. The Wu thermocouple did not use dispersionhardening in both legs and did not face the challenge of obtaining arepeatable output signal from the thermocouple at an extended range.

This patent outlines a thermocouple sensor with a sheath capable ofextending the operating range of this class of sensor up to 1700° C.(3092° F.).

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide sensorwith a rugged sheath exhibiting high mechanical hardness to protectionof the sensor and/or conductors connected thereto.

A further object of the present invention is to provide a sensor withenhanced high temperature operating characteristics and long term,stable output and minimum drift in EMF.

Another object of the present invention is to provide an extendedtemperature range EMF device that can be configured as a thermocouplefor the purpose of measuring localized temperature. Still another objectof the present invention is to provide a device which in inverse modeoperation can be used as a voltage generator in the presence of atemperature gradient.

Yet still another object of the present invention is to provide anextended temperature range EMF device which in dual mode operation canbe implemented as a heat flux sensor. A further object of the inventionis to provide a device which can be a part of a parallel array ofdevices to create a thermopile of increased sensitivity or voltageoutput.

And still yet another object of the present invention is to provide anEMF device implementing electronics to condition the output and convertit to specified calibrated reference data, or to an industry standardsuch as a National Institute of Standards and Technology reference or anInternational Electrotechnical Commission reference.

And yet another object of the present invention is to provide a methodfor the production of a cost effective, high reliability, stable EMFdevices with an operating range of up to 1700° C. (3092° F.) in hostileenvironments.

These and other objects of the present invention are achieved byproviding a sensor which is resistant to degradation at high temperaturehaving two components in contact with each other, with two conductiveleads for transmitting an electric signal. The first component is formedof at least one first noble metal and an oxide selected from the groupconsisting of yttrium oxide, cerium oxide, zirconium oxide, andcombinations of these, while the second component is formed of at leastone second noble metal, different than the first noble metal, and anoxide selected from the group consisting of yttrium oxide, cerium oxide,zirconium oxide, and combinations of these.

It has been determined that the combination of a noble metal and anoxide selected from the group consisting of yttrium oxide, cerium oxide,zirconium oxide, and combinations of these exhibits both high mechanicalstrength and high electrical conductive properties.

The objects of the present invention are further achieved in anotherembodiment by providing a sensor which is resistant to degradation athigh temperature having two components in contact with each other, eachcomponent capable of transmitting an electric signal. The firstcomponent is formed of an oxide selected from the group consisting oftransition element oxides and rare earth metal oxides, and combinationsof these, where the oxide is dispersion hardened within the grainboundary and within the main body of a first base metal selected fromthe group consisting of the noble metals and the precious metals, andcombination of these. The second component is formed of an oxideselected from the group consisting of the transitional metal oxides andthe rare earth metal oxides, and combinations of these, where the oxideis dispersion hardened within the grain boundary and within the mainbody of a second base metal, that is different from the first basemetal, selected from the group consisting of the noble metals and theprecious metals, and combination of these.

The objects of the present invention are achieved in yet anotherembodiment by a method of manufacturing a high temperature resistantsensor by forming a first component from at least one first noble metaland an oxide selected from the group consisting of yttrium oxide, ceriumoxide, zirconium oxide, and combinations of these and a second componentfrom at least at least one second noble metal, different than the firstnoble metal, and an oxide selected from the group consisting of yttriumoxide, cerium oxide, zirconium oxide, and combinations of these. Next,joining said first and second components and attaching a pair of leadsconnected one each to the first and second component for transmittingelectrical signals.

The objects of the present invention are further achieved in anotherembodiment by providing a sensor which is resistant to degradation athigh temperature having a first and second component, each adapted totransmitting an electrical signal. The first component is formed of anoxide selected from the group consisting of yttrium oxide, cerium oxide,zirconium oxide, and combinations of these, where the oxide isdispersion hardened within the grain boundary and within the main bodyof platinum. The second component formed of an oxide selected from thegroup consisting of yttrium oxide, cerium oxide, zirconium oxide, andcombinations of these, where the oxide is dispersion hardened within thegrain boundary and within the main body of a platinum rhodium alloy.This sensor also has a transducer to receive an electrical signal.

The objects of the present invention, in each of the above describedembodiments, could be further achieved where an electrical signalcomprises a varying voltage and is applied to a transducer. Thetransducer may be a temperature measuring device. The output of thetransducer may correlate to a temperature or a logic function applied tospecific calibration data to determine the temperature. The transduceroutput could correlate to a standard reference output, or couldcorrelate specifically to a National Institute of Standards andTechnology or to an International Electrotechnical Commission reference.

The objects of the present invention, in each of the above describedembodiments could be additionally achieved where an electrical signalcomprises a varying voltage and is applied to a transducer. Thetransducer may be a conditioner. The output of the conditioner may be aconditioned varying voltage which is adapted to power electronics.

In still another advantageous embodiment a sensor is providedcomprising, a first component formed from a first component material,and a first conductor formed from a first conductor material, the firstconductor electrically connected to the first component. The sensorfurther comprises, a second component in electrical contact with thefirst component, the second component formed from a second componentmaterial, and a second conductor formed from a second conductormaterial, the second conductor electrically connected to the secondcomponent. The sensor still further comprises, a sheath enclosing atleast the first component and the second component, the sheath formed ofa sheath material having at least one noble metal and an oxide selectedfrom the group consisting of yttrium oxide, cerium oxide, zirconiumoxide, and combinations of these.

It has further been determined that any standard thermocouple devicesuch as for instance but not limited to a standard type “K” thermocouplemay be effectively utilized with the above-listed sheath material thatexhibits high mechanical strength.

In yet another advantageous embodiment a method for manufacturing asensor is provided comprising the steps of, forming a first componentfrom a first component material, forming a first conductor from a firstconductor material, and electrically connecting a first conductor to thefirst component. The method further comprises the steps of, forming asecond component from a second component material, forming a secondconductor from a second conductor material, and electrically connectinga second conductor to the second component. The method still furthercomprises the steps of, electrically contacting the first component withthe second component to form a junction where the first component meetsthe second component, forming a sheath of a material having at least onenoble metal and an oxide selected from the group consisting of yttriumoxide, cerium oxide, zirconium oxide, and combinations of these, andenclosing at least the first component and the second component in thesheath.

In still another advantageous embodiment a sensor which is resistant todegradation at high temperature is provided comprising, a firstcomponent formed from at least a first noble metal and an oxide selectedfrom the group consisting of yttrium oxide, cerium oxide, zirconiumoxide, and combinations of these, and a first conductor formed from afirst conductor material, the first conductor electrically connected tothe first component. The sensor further comprises, a second component incontact with the first component, the second component formed from atleast at least a second noble metal, different than the first noblemetal, and an oxide selected from the group consisting of yttrium oxide,cerium oxide, zirconium oxide, and combinations of these, and a secondconductor formed from a second conductor material, the second conductorelectrically connected to the second component. The sensor still furthercomprises, a sheath enclosing the first and second conductors, thesheath formed of a sheath material having at least a third noble metaland an oxide selected from the group consisting of yttrium oxide, ceriumoxide, zirconium oxide, and combinations of these.

In yet another advantageous embodiment a sensor is provided comprising,a first component formed from a first component material, and a firstconductor formed from a first conductor material, the first conductorelectrically connected to the first component. The sensor furthercomprises, a second component in electrical contact with the firstcomponent, the second component formed from a second component material,and a second conductor formed from a second conductor material, thesecond conductor electrically connected to the second component. Thesensor still further comprises, a sheath enclosing at least the firstconductor and the second conductor, the sheath formed of a sheathmaterial having at least one noble metal and an oxide selected from thegroup consisting of yttrium oxide, cerium oxide, zirconium oxide, andcombinations of these.

The invention and its particular features and advantages will becomemore apparent from the following detailed description considered withreference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of one advantageous embodiment of the presentinvention.

FIG. 1A is a block diagram of the advantageous embodiment according toFIG. 1.

FIG. 1B is a block diagram of the advantageous embodiment according toFIG. 1.

FIG. 2 is a block diagram according to another advantageous embodimentof the present invention.

FIG. 3 is an illustration of a transmit lead module according to FIG. 2.

FIG. 4 is a block diagram of another embodiment of the present inventionaccording to FIG. 2.

FIG. 5 is a block diagram of another embodiment of the present inventionaccording to FIG. 2.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring now to the drawings, wherein like reference numerals designatecorresponding structure throughout the views.

FIG. 1 is a block diagram illustrating one preferred embodiment of thepresent invention showing sensor 10. A first component 11 is illustratedin contact with a second component 12 forming a junction 19. Also shownare first conductor 23 and second conductor 24 electrical connected tothe first component 11 and the second component 12 respectively.

Sensor 10 is further illustrated in FIG. 1 with insulation 21. Theinsulation may comprise any suitable insulating material desiredincluding but not limited to a refractory ceramic material such as forinstance, Al₂O₃ or MgO. Although insulation 21 is shown in FIG. 1enclosing sensor 10, it is contemplated that insulation 21 may onlyenclose a portion of sensor 10, such as for instance, first and secondconductors 23, 24 or first and second component 11, 12 or any otherportion thereof.

Also illustrated in FIG. 1 is sheath 20 shown enclosing insulation 21.Sheath 20 may comprise, for instance, a noble metal such as a platinumgroup metal, and a metal oxide selected from the group consisting ofyttrium oxide, cerium oxide, zirconium oxide, and combinations of these.It is further contemplated that through an annealing process calleddispersion hardening, the metal oxides may be deposited within the grainboundaries and main body of the noble metal. This process produces asheath 20 formed of a highly stable material capable of withstandingmechanical loads and chemical attacks at elevated temperatures whilemaintaining its internal chemical integrity. This is highly desirableespecially in hostile environments where the sensor is subjected tomechanical stress and/or a wide range of temperatures.

In one preferred embodiment sheath 20 comprises platinum, having yttriumoxide or yttrium and zirconium oxide dispersed within its grain boundaryand within the main body. In another preferred embodiment the sheath 20comprises a platinum rhodium alloy (10% rhodium) having yttrium oxide oryttrium and zirconium oxide dispersed within its grain boundary andwithin the main body. Although sheath 20 is shown in FIG. 1 enclosingsensor 10, it is contemplated that sheath 20 may only enclose a portionof sensor 10, such as for instance, first and second conductors 23, 24(FIG. 1A) or first and second component 11, 12 (FIG. 1B) or any otherportion thereof.

It is contemplated that the first and second components 11, 12 alongwith the first and second conductors 23, 24 may comprise for instance,any standard thermocouple device such as for instance but not limited toa standard type “K” thermocouple with the first and second conductors23, 24 enclosed by the sheath 20, which has been previously described.

Still further illustrated in FIG. 1 is transmit lead module 30 thatincludes transmit leads 13, 14. Also illustrated in FIG. 1 is transmitlead module insulation 21′ enclosing transmit leads 13, 14. Transmitlead module insulation 21′ may comprise any material as previouslydescribed in connection with insulation 21. Further illustrated istransmit lead module sheath 20′, which encloses transmit lead moduleinsulation 21′. Transmit lead module sheath 20′ may also comprise anymaterial as previously described in connection with sheath 20. It isfurther contemplated that, although only one transmit lead module 30 isshown in FIG. 1, any number may be connected together, for instance inan end-to-end fashion, as required depending upon the installation.

Referring now to FIGS. 2-6, a sensor 10, is made of components of aclass of materials chosen to be resistant to degradation in hightemperature operation up to 1700° C. (3092° F.). The first component 11and the second component 12 are dissimilar materials within a class. Theclass of materials is made up of one or more base metals, usually anoble metal, with metal oxides selected from the group consisting ofyttrium oxide, cerium oxide, zirconium oxide, and combinations of these.Through an annealing process not described herein, the metal oxides maybe deposited within the grain boundaries and main body of the basemetal. The process is called dispersion hardening. This has the effectof stabilizing the grain structure of the material at extendedtemperatures and provides an increased resistance path for impurities.The net effect is a highly stable material capable of withstandingmechanical loads and chemical attacks at elevated temperatures whilemaintaining its internal chemical integrity. This provides thefoundation for an extended temperature range EMF device with long term,stable output and minimum drift in EMF.

The base metal may be chosen from the noble metals such as for instance,from the platinum group metals. In one preferred embodiment the firstcomponent 11 comprises platinum, having yttrium oxide or yttrium andzirconium oxide dispersed within its grain boundary and within the mainbody. In another preferred embodiment the second component 12 comprisesa platinum rhodium alloy (10% rhodium) having yttrium oxide or yttriumand zirconium oxide dispersed within its grain boundary and within themain body.

The basic shape of components 11, 12 is not limited. The components canhave a variety of cross sectional geometries as desired for theparticular application. Furthermore, the components may be manufacturedby depositing the material onto a substrate. The substrate may comprisethe same class of material as the components, having at least one noblemetal with a metal oxide from the group consisting of yttrium oxide,cerium oxide, zirconium oxide, and combinations of these, dispersedwithin its grain boundary and within the main body. Refractory materialsof varying compositions such Al₂O₃ or MgO may also be used as thesubstrate.

Many varying structures may be utilized to for components 11, 12. Allthat is necessary is that the components contact each other such thatthey share a junction 19. In addition each component must also have asecond junction end that does not contact the other component. In oneadvantageous embodiment first conductor 23 and second conductor 24 fortransmitting electrical energy, may be electrically connected betweeneach junction end and a transducer/conditioner 15. In addition, transmitleads 13, 14 may comprise different material compositions than the firstand second conductors 23, 24 creating a junction at 17, 18. Anotherpossible junction point 25, 26 may comprise still another differingmaterial composition than the transmit leads 13, 14. However, the sensorcould be formed such that one or both of the wire components maytransmit electrical energy to the transducer/conditioner 15. It shouldalso be noted that the electrical energy may be electrically compensatedfor these junction points of differing compositions.

The components of the sensor may also be housed in a sheath 20 toprotect the device from the hostile environments in which the sensoroperates. The sheath 20 may be formed of a high temperature alloy ormade from the same class of material as the components, having at leastone noble metal with a metal oxide from the group consisting of yttriumoxide, cerium oxide, zirconium oxide, and combinations of these,dispersed within its grain boundary and within the main body.

As illustrated in FIG. 2, the sensor may be insulated between thecomponents 11, 12 and the sheath 20. The insulation 21 may be arefractory ceramic material such as Al₂O₃ or MgO.

In operation, the components of the sensor are exposed to a temperaturegradient ΔT. The first component 11 interacts with the second component12 at the junction 19 such that electrical energy/signal or EMF isgenerated based upon the temperature gradient ΔT. The electrical signalmay comprise, for instance, a varying voltage (Δv). The electricalsignal may then be transmitted to the transducer/conditioner 15.

In one advantageous embodiment as illustrated in FIG. 2, first andsecond conductors 23, 24 terminate at junctions 17, 18 respectively.From junctions 17, 18 transmit leads 13, 14 extend to junction point 25,26 to terminate at transducer/conditioner 15. In FIG. 2, transmit leads13, 14 are illustrated located inside transmit lead module 30.

The structure and method for manufacturing transmit lead module 30 inone advantageous embodiment as illustrated in FIG. 3, will now bedescribed. Transmit lead module 30 generally comprises: transmit leads13, 14; insulating layer 32; and outer layer 34. Transmit leads 13, 14may comprise any suitable materials as previously described herein inconnection with FIG. 2. Insulating layer 32 may comprise, for instance,a refractory ceramic material such as Al₂O₃ or MgO generally formed intoan elongated member such as a cylinder. Also illustrated in FIG. 3 aretwo through holes 36, 38 extending axially through the length ofinsulating layer 32 through which transmit leads 13, 14 are respectivelyinserted. Surrounding and encasing insulating layer 32 is outer layer34. Outer layer 34 may comprise in one advantageous embodiment, the samematerial as one of transmit leads 13, 14. One advantage realized fromthis particular configuration is that one of the electricallead/transmit lead cold junctions may be eliminated.

Once the insulating layer 32 containing transmit leads 13, 14 isinserted into outer layer 34, the entire transmit lead module 30 may beswaged or drawn. The compression of transmit lead module 30 causesinsulating layer 32 to be compressed and tightly crushed such that airis evacuated and any air pockets within transmit lead module 30 may beeffectively eliminated.

Any number of transmit lead modules 30 may then be tied togetherdepending upon the distance between the sensor and thetransducer/conditioner 15. This provides versatility and modularity tothe system as the installer may utilize any number of transmit leadmodules 30 in an installation. Transmit lead modules 30 may further bebent and manipulated as desired to custom fit a particular installation.The outer layer 34 being rigid further provides protection for transmitleads 13, 14 from wear, abrasion and repeated bending and/or flexing.This will increase the effective lifespan of the system. In addition, aspreviously discussed, transmit lead modules 30 may be joined togetherwith each other in an end-to-end fashion with transmit leads 13, 14 inthe first transmit lead module 30 forming a junction with transmit leads13, 14 in the second transmit lead module 30. However, when the exteriorlayer 34 for both the first and second transmit lead modules 30comprises the same material as one of the transmit leads 13, 14, thenthe corresponding transmit lead junction may be eliminated furthersimplifying the system.

Whenever transmit leads are joined of differing composition this createsa potential for a secondary, tertiary, etc. EMF voltage which reactswith the primary EMF resulting in a shift in output. To maintain themaximum accuracy the cold junction temperature must be measured with anexternal EMF device whose output is used to correct for the error eitherby an external user device or implemented in the logic function.

If the sensor is arranged as a thermocouple for the purpose of measuringlocalized temperature, the varying voltage will correlate to atemperature. The output from the transducer would then be a temperaturereading from a temperature measuring device 16. (FIG. 4). Certainreference conversions exist to determine temperature from a varyingvoltage output from a thermocouple. These standards are determined bysuch agencies as the National Institute of Standards and Technology andthe International Electrotechnical Commission. The standards are basedupon the properties of the material of the thermocouple components andthe temperature ranges to which the thermocouple is subjected.

No standard reference to correlate the varying voltage to a temperaturereading is available for the class of materials used in the presentinvention. Accordingly, a logic function 40 (FIG. 5) can be applied tothe varying voltage to convert it to one of the known industry standardsand corrects for cold junction potential generated or created atjunction 17, 18 and/or the transition at junction point 25, 26. Thiswould make the thermocouple an off the shelf component.

The output of the sensors need not be converted to an NIST standard tomake it usable. In some applications, calibration data can be suppliedalong with a basic algorithm which would be implemented in a controlsystem developed by an outside source. In this case the algorithms wouldbe customized to the user's particular application.

In inverse mode operation, the sensor can be used as a voltage generatorin the presence of a temperature gradient. The varying voltage outputcould be conditioned as a power source to power electronics negating theneed for an internal power supply.

In dual mode operation, the sensor could be implemented as a heat fluxsensor. Under either application, measuring temperature or as a voltagegenerator, the sensor could be configured as a part of a parallel arrayof sensors to create a thermopile of increased sensitivity or voltageoutput.

Although the invention has been described with reference to particularingredients and formulations and the like, these are not intended toexhaust all possible arrangements or features, and indeed many othermodifications and variations will be ascertainable to those of skill inthe art.

1. A sensor comprising: a first component formed from a first componentmaterial; a first conductor formed from a first conductor material, saidfirst conductor electrically connected to said first component; a secondcomponent in electrical contact with said first component, said secondcomponent formed from a second component material; a second conductorformed from a second conductor material, said second conductorelectrically connected to said second component; a sheath enclosing atleast said first component and said second component, said sheath formedof a sheath material having a platinum rhodium alloy, with at least 10%rhodium, and an oxide selected from the group consisting of yttriumoxide, cerium oxide, zirconium oxide, and combinations of these; andsaid oxide is dispersion hardened within grain boundaries and a mainbody portion of the noble metal.
 2. The sensor of claim 1 wherein thefirst conductor material and the second conductor material are the same.3. The sensor of claim 2 wherein the first conductor material and thesecond conductor material are different than the sheath material.
 4. Thesensor of claim 1 wherein the first component material comprises atleast a first component noble metal and an oxide selected from the groupconsisting of yttrium oxide, cerium oxide, zirconium oxide, andcombinations of these.
 5. The sensor of claim 4 wherein the secondcomponent material comprises at least a second component noble metal,different than the first component noble metal, and an oxide selectedfrom the group consisting of yttrium oxide, cerium oxide, zirconiumoxide, and combinations of these.
 6. The sensor of claim 1 furthercomprising an insulting layer enclosing said first and secondconductors.
 7. The sensor of claim 6 wherein said insulating layer isenclosed by said sheath.
 8. A method for manufacturing a sensorcomprising the steps of: providing a first component of a firstcomponent material; electrically connecting a first conductor to thefirst component; providing a second component of a second componentmaterial; electrically connecting a second conductor to the secondcomponent; electrically contacting the first component with the secondcomponent to form a junction where the first component meets the secondcomponent; forming a sheath of a material having a platinum rhodiumalloy, with at least 10% rhodium, and an oxide selected from the groupconsisting of yttrium oxide, cerium oxide, zirconium oxide, andcombinations of these; dispersion hardening the oxide within grainboundaries and a main body portion of the noble metal; and enclosing atleast the first component and the second component in the sheath.
 9. Themethod of claim 8 wherein the first conductor material and the secondconductor material are the same.
 10. The method of claim 9 wherein thefirst conductor material and the second conductor material are differentthan the sheath material.
 11. The method of claim 10 further comprisingthe step of enclosing the first conductor and the second conductor withan insulating layer.
 12. The method of claim 11 wherein the sheathencloses the insulating layer.
 13. A sensor which is resistant todegradation at high temperature comprising: a first component formedfrom at least a first noble metal and an oxide selected from the groupconsisting of yttrium oxide, cerium oxide, zirconium oxide, andcombinations of these; a first conductor formed from a first conductormaterial, said first conductor electrically connected to said firstcomponent; a second component in contact with said first component, saidsecond component formed from at least at least a second noble metal,different than the first noble metal, and an oxide selected from thegroup consisting of yttrium oxide, cerium oxide, zirconium oxide, andcombinations of these; a second conductor formed from a second conductormaterial, said second conductor electrically connected to said secondcomponent; a sheath enclosing said first and second conductors, saidsheath formed of a sheath material having a platinum rhodium alloy, withat least 10% rhodium, and an oxide selected from the group consisting ofyttrium oxide, cerium oxide, zirconium oxide, and combinations of these;and said oxide is dispersion hardened within grain boundaries and a mainbody portion of the noble metal.
 14. The sensor according to claim 13further comprising: a transmit lead module having, a first transmit leadformed of a first transmit lead material, for electrically connecting tosaid first conductor; a second transmit lead formed of a second transmitlead material, for electrically connecting to said second conductor; anda transmit lead module sheath enclosing said first transmit lead andsaid second transmit lead.
 15. The sensor of claim 14 wherein saidtransmit lead module sheath is formed of a fourth noble metal and anoxide selected from the group consisting of yt-trium oxide, ceriumoxide, zirconium oxide, and combinations of these.
 16. The sensor ofclaim 15 wherein said transmit lead module further comprises aninsulating layer enclosing said first transmit lead and said secondtransmit lead.
 17. The sensor of claim 16 wherein said transmit leadmodule sheath encloses said insulating layer.
 18. The sensor of claim 13wherein the first conductor material and the second conductor materialare the same.
 19. The sensor of claim 18 wherein the first conductormaterial and the second conductor material are different than the sheathmaterial.
 20. A sensor comprising: a first component formed from a firstcomponent material; a first conductor formed from a first conductormaterial, said first conductor electrically connected to said firstcomponent; a second component in electrical contact with said firstcomponent, said second component formed from a second componentmaterial; a second conductor formed from a second conductor material,said second conductor electrically connected to said second component; asheath enclosing at least said first conductor and said secondconductor, said sheath formed of a sheath material having a platinumrhodium alloy, with at least 10% rhodium, and an oxide selected from thegroup consisting of yttrium oxide, cerium oxide, zirconium oxide, andcombinations of these; and said oxide is dispersion hardened withingrain boundaries and a main body portion of the noble metal.
 21. Asensor comprising: a first component formed from a first componentmaterial; a first conductor formed from a first conductor material, saidfirst conductor electrically connected to said first component; a secondcomponent in electrical contact with said first component, said secondcomponent formed from a second component material; a second conductorformed from a second conductor material, said second conductorelectrically connected to said second component; and a sheath,electrically insulated from and enclosing at least said first componentand said second component, said sheath formed of a sheath materialhaving a platinum rhodium alloy, with at least 10% rhodium, and an oxideselected from the group consisting of yttrium oxide, cerium oxide,zirconium oxide, and combinations of these; said sheath having a highermelting point that said first and second components.
 22. A sensorcomprising: a first component formed from a first component material; afirst conductor formed from a first conductor material, said firstconductor electrically connected to said first component; a secondcomponent in electrical contact with said first component, said secondcomponent formed from a second component material; a second conductorformed from a second conductor material, said second conductorelectrically connected to said second component; a sheath, electricallyinsulated from and enclosing at least said first conductor and saidsecond conductor, said sheath formed of a sheath material having aplatinum rhodium alloy, with at least 10% rhodium, and an oxide selectedfrom the group consisting of yttrium oxide, cerium oxide, zirconiumoxide, and combinations of these; said sheath having a higher meltingpoint that said first and second conductors.